Counterbalancing apparatus for a pivotal panel



April 15, 1969 .1. CADIOU 7 3,43

COUNTERBALANCING APPARATUS FOR A PIVOTAL PANEL Filed Dec. 6, 1966 Sheetof 2 April 15, 1969 J. CADIOU 3,438,152

COUNTERBALANCING APPARATUS FOR A PIVOTAL PANEL Filed Dec. 6, 1966 Sheet3 of 2 United States Patent 3,2 Int. Cl. EOSf 1/10, 1/08 US. Cl. 49386 3Claims ABSTRACT OF THE DISCLOSURE A pivotally mounted panel, such as thelid of an automobile trunk, is counterbalanced by two lengths ofresilient material, which may be formed from a single steel rod bentabout its midpoint, disposed parallel to the pivotal axis of the lid andin close proximity to each other, each length at one end being bent atright angles and secured, the one to the panel or lid and the other tothe automobile frame. At the other or common end the two rods meet attheir junction and are pivotally mounted to the automobile frame or lidabout an axis parallel to the pivotal axis of the panel. When the lid isopened, each rod twists at an angle equal to half that of the pivotalangle of the panel or lid and thus provides a counterbalancing force tothe Weight of the lid.

The present invention relates to apparatus for counterbalancing a panelpivotally mounted with respect to a fixed frame and more particularly toapparatus which can be mounted in a small space and in which thecounterbalance force remains practically constant during thedisplacement of the panel.

The present invention provides apparatus for counterbalancing a panelpivotally mounted with respect to a fixed frame, comprising two lengthsof resilient material each having a portion parallel to a correspondingportion of the other length and having a portion substantially normal tosaid parallel portion, constraining means for constraining therespective free end of each said normal portion with respect to thepanel and the fixed frame, and pivotal means for constraining the endsof said parallel portions remote from said normal portion, with respectto one another and pivotally mountable with respect to the frame.

An embodiment of apparatus for counterbalancing a back door of acommercial vehicle in accordance with the present invention, will now bedescribed by way of example with reference to the accompanyingdiagrammatic drawings, in which;

FIGURE 1 is a perspective view of the counterbalancing apparatus showinga counterbalance spring attached to portions of a back door and bodyworkof a commercial vehicle.

FIGURE 2 is a side elevation of the apparatus shown in FIGURE 1.

FIGURE 3 is a plan view of an alternative counterbalance spring; and

FIGURE 4 is a section along the line 11-11 of FIG- UR'E 3.

In FIGURES 1 and 2, a back door 1 is pivotally connected to the bodywork3 of a vehicle by means of hinges 2 along a horizontal pivotal axis.

The door 1 is counterbalanced so as to permit easy opening and closingthereof. The counterbalancing apparatus consists of a resilient steelrod which has been bent double to form two equal parallel lengths 4a and4b, whose end portions 40 and 4d have been bent outwards at right angleswith a respect to the lengths 4a and 4b.

3,438,152 Patented Apr. 15, 1969 'In order to strengthen the endportions 4c and 4d of the rod and thereby to restrain them from bendingthese portions are threaded into two tubes 5a and 5b respectively whichextend around the elbows connecting the end portions to the parallellengths 4a and 4b.

The free ends of the tubes 5a and 5b are flattened and provided with anaperture so that they can be pivotally connected to the door 1 and thebodywork 3 respectively, by means of screws or pins 6 engaging therespective apertures.

The two lengths 4a and 4b disposed parallel to the horizontal hinge axisare attached at their juncture 4e to the bodywork 3 by a right-angledbracket or tab 7 one of whose lengths has an aperture 8 which is engagedwith the rod at the juncture 4e.

The portions of the lengths 4a and 4b just below the elbows are enclosedby the tubes 5a and 5b which are connected together just below theelbows by a connector 9 not fixed to the bodywork 3 but which is weldedto the tube 5b, the tube 5b being connected to the bodywork.

The lowering of the door 1 causes torsional strain the length 4a of therod at the same time allowing the juncture 4e to pivot in the aperture 8to cause torsion in the length 412 also. The torsion thus caused willtend to oppose the lowering of the door 1.

As shown in FIGURE 2, when the door is opened the elbows and theconnector 9 move away from the bodywork. As a result, if an accidentalpush is exerted on these elbow portions, for example while loading thevehicle, the door will be caused to shut rapidly. In addition the actionof a wind can equally cause the unexpected closure of the door.

In order to prevent undesired closure of the door 1, a latch 10 isprovided which is pivotally mounted by means of a pivot 11 on thebodywork 3. This latch 10 has a shaped slot 13a, 13b in which a pin 12engages, the pin 12 being rigid with the tube 5b. The portion 13a of theslot provides a locking position for the pin 12 while the portion 13b ofthe slot provides a release position for the pin 12.

Upon opening the door the latch 10 pivots downwards under its own weightso that the pin 12 engages with the portion 13a of the slot therebylatching the door in an open position. The door can be released bymaking the latch 10 pivot upwards to cause the pin 12 to engage theportion 13b.

A flexible protective sheath 14 covers part of the lengths 4a and 4b ofthe rod.

FIGURES 3 and 4 show how counterbalancing can be provided using two rods15a and 15b having square cross-sections. Each rod has a portioncorresponding to one of the portions 4a and 4b of the rod in FIGURES 1and 2 and portions at right angles (not shown) corresponding to theportions 40 and 4d.

The portions of the rods 15a and 15b corresponding to portions 4a and 4bare parallel and covered by a protective sheath 14 while their free endsare encased in connecting member 16 and are held therein by pins 17.

The member 16 is rigid with pin 18 which is pivotally mounted in theaperture of a tab 7 corresponding to the aperture '8 and tab 7 ofFIGURE 1. The tab 7 is secured to the bodywork 3 by a nut 19.

I claim:

1. In combination a fixed frame,

a panel pivotally connected to said fixed frame,

two lengths of resilient material each having a portion parallel andadjacent to a corresponding portion of the other length and having a.portion substantially normal to said parallel portion,

two constraining members constraining respective free ends of saidnormal portions with respect to the panel and the fixed frame, and

pivot means pivoting the ends of the said parallel portions remote fromsaid normal portions with respect to one another and with respect to theframe.

'2. In combination a fixed frame, a panel pivotal-1y connected to saidfixed frame, a single resilient member bent substantially about its midpoint to form two lengths each having a portion parallel to acorresponding portion of the other length and each having a secondportion extending substantially perpendicular to said parallel portion,to a free end, flexible protective sheath means covering said parallelportions, one of said second portions being secured to said panel at itsend and one to said fixed frame, at its end said bend at said midpointbeing pivotally connected with said frame so that said parallel portionsare disposed substantially parallel to the pivotal axis of the panel, aconnector constraining the ends of said parallel portions remote fromsaid bend with respect to each other.

3. The combination of claim -1 wherein e'ach of said perpendicularportions is held within a hollow sleeve, one sleeve being secured tosaid frame and one to said panel, a latch secured to said frame, -a pinextending from said sleeve secured to said frame, disposed incooperating relation to said latch whereby said latch locksautomatically when said panel is opened.

References Cited UNITED STATES PATENTS 2,602,957 7/ 1952 Anderson 49-386 XR 2,810,153 10/1957 Semar 49-386 XR 2,909,254 10/1959 Hallock16--'19O XR 3,153,255 10/ 1964 Bostwick 49386 XR KENNETH D'OWNEY,Primary Examiner.

US. Cl. X.R. 1'6-75

